package top.whysu.gps.utils;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;

public class Coder {
    /**
     * 16λ
     */
    private String key = "<aes@leelen.com>";
    private byte[] keyBytes;

    public Coder(String key) {
        this.key = key;
    }

    public byte[] encrypt(byte[] clearBytes) throws Exception {
        keyBytes = key.getBytes();
        return encrypt(keyBytes, clearBytes);
    }

    public String encrypt(String seed, String cleartext) throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }

    public String encrypt(String cleartext) throws Exception {
        byte[] rawKey = getRawKey(key.getBytes());
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }

    public String encryptByKey(String cleartext) throws Exception {
        byte[] result = encrypt(key.getBytes(), cleartext.getBytes());
        return toHex(result);
    }

    public byte[] encroyByKeyByte(byte[] secretByte, byte[] clearByte) throws Exception {
        return encrypt(secretByte, clearByte);
    }

    public byte[] decrypt(byte[] encrypted) throws Exception {
        keyBytes = key.getBytes();
        return decrypt(keyBytes, encrypted);
    }

    public String decrypt(String seed, String encrypted) throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }

    public String decrypt(String encrypted) throws Exception {
        byte[] rawKey = getRawKey(key.getBytes());
        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }

    public String decryptByKey(String encrypted) throws Exception {
        byte[] enc = encrypted.getBytes();
        byte[] result = decrypt(key.getBytes(), enc);
        return new String(result);
    }

    private byte[] getRawKey(byte[] seed) throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
        sr.setSeed(seed);
        // 192 and 256 bits may not be available
        kgen.init(128, sr);
        SecretKey skey = kgen.generateKey();
        return skey.getEncoded();
    }

    public byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        return cipher.doFinal(clear);
    }

    public byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        return cipher.doFinal(encrypted);
    }

    public String toHex(String txt) {
        return toHex(txt.getBytes());
    }

    public String fromHex(String hex) {
        return new String(toByte(hex));
    }

    public byte[] toByte(String hexString) {
        int len = hexString.length() / 2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++) {
            result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2), 16).byteValue();
        }
        return result;
    }

    public String toHex(byte[] buf) {
        if (buf == null) {
            return "";
        }
        StringBuffer result = new StringBuffer(2 * buf.length);
        for (int i = 0; i < buf.length; i++) {
            appendHex(result, buf[i]);
        }
        return result.toString();
    }

    private final static String HEX = "0123456789ABCDEF";

    private void appendHex(StringBuffer sb, byte b) {
        sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
    }

    public String getKey() {
        return key;
    }

    public void setKey(String key) {
        this.key = key;
    }
}